Stuart J. O'Toole

Surfactant Decreases pulmonary vascular resistance and increases pulmonary blood flow in the fetal lamb model of congenital diaphragmatic hernia

INTRODUCTION Experiments using animal models of neonatal respiratory distress syndrome have shown a decrease in pulmonary vascular resistance (PVR) with surfactant replacement, whereas studies with the lamb model of congenital diaphragmatic hernia (CDH) have demonstrated improvement in oxygenation and lung mechanics with this therapy. The aim of the present study was to measure the effects of surfactant replacement therapy on the pulmonary hemodynamics of the lamb model of CDH. METHODS Ten lambs with surgically created CDH and five control lambs were instrumented at term, with the placental circulation intact. Ultrasonic flow probes were positioned around the main pulmonary artery and the common origin of the left and right pulmonary arteries to record total lung and main pulmonary artery blood flow. Catheters were inserted to record systemic, pulmonary, and left atrial pressure. Five CDH animals received 50 mg/kg of surfactant by tracheal instillation just before delivery. All 15 animals were then ventilated for 4 hours. RESULTS Correcting the surfactant deficiency in the CDH lamb resulted in a significant increase in pulmonary blood flow, a decrease in PVR, and a reduction in right-to-left shunting. These improvements in hemodynamics were associated with a significant improvement in gas exchange over 4 hours. CONCLUSION The fetal lamb model of CDH has elevated PVR in comparison to controls. Prophylactic surfactant therapy reduces this resistance and dramatically increases pulmonary blood flow while reducing extrapulmonary shunt. A surfactant deficiency may be partially responsible for the persistent pulmonary hypertension in neonates with CDH.

Insurance-related differences in the presentation of pediatric appendicitis

In the pediatric population, there is strong evidence to suggest that a delay in treatment results in an increased risk of appendiceal perforation. However, it is not clear whether this delay arises from the parent seeking medical advice, the referring physician seeking surgical consultation, or the surgeon deciding to operate. To resolve this issue, the authors performed a retrospective chart review of all cases of confirmed acute appendicitis that presented to the pediatric surgical service of the Childrens Hospital of Buffalo during a 4-year period (January 1990 through December 1993). All children (< or = 16 years of age) were categorized with respect to type of insurance coverage:Medicaid (or uninsured), health maintenance organization (HMO), or private fee-for-service. Their time until emergency room (ER) presentation, operating room (OR) presentation, and hospital discharge were recorded and compared. Their complications and perforation rates also were noted. Two hundred eighty-eight cases were reviewed. The rate of appendiceal perforation was significantly higher among the Medicaid patients (Medicaid, 44%; HMO, 27%; private, 23%; P < .05); their duration of symptoms before presentation was significantly longer (Medicaid, 47.3 +/- 4.1 hours; HMO, 29.3 +/- 1.9 hours; private, 23.1 +/- 2.5 hours; P < .01), and their hospital stay was longer (Medicaid, 7.9 +/- 0.9 days; HMO, 4.8 +/- 0.27 days; private, 4.6 +/- 0.44 days; P < .01). However, there were no significant differences in the time from presentation to the ER until definitive surgery in the OR. Children covered by Medicaid (or uninsured) presented later, had a higher risk of appendiceal perforation, and required a longer hospital stay. The parents of these children either failed to recognize the significance of their childrens symptoms, or delayed seeking medical advice because of financial or logistical reasons. The gatekeeper consultation, required by the health maintenance organizations (HMO) did not result in a delay in presentation or have a negative impact on morbidity. Providing easier access to a primary care physician and improving parental health education/awareness may shorten the time until presentation for the uninsured/Medicaid patient.

Cervical ECMO cannula placement in infants and children: Recommendations for assessment of adequate positioning and function

BACKGROUND/PURPOSE Cervical extracorporeal membrane oxygenation (ECMO) cannula position is often difficult to confirm by chest x-ray alone. Malposition requires a second surgery to rectify the problem. Reoperation places the patient at risk for infection, bleeding, or death. This study analyzes indications for cannula repositioning and suggests an alternative standard for intraoperative evaluation of catheter function as it relates to position. METHODS The authors reviewed charts of 73 patients placed on arterio-venous ECMO through cervical vascular access. Reasons for repositioning of either cannula at the initial surgery or postoperatively were recorded. RESULTS Of 73 patients, 18 (24.6%) required either arterial cannula or venous cannula repositioning. In 10 (55%) of these patients, cannula malposition was not detected by chest x-ray during the initial cannulation, and they therefore required a second cervical exploration for repositioning. CONCLUSIONS Chest x-ray is not sensitive in demonstrating malpositioned cervical ECMO cannulae. Two-dimensional ECHO before wound closure, may be a superior, more cost effective means of assessing cannula placement and function than x-ray alone. Confirmation of cannula position and function, before wound closure, would reduce the risks involved with cervical reexploration.

Meconium ileus: antenatal diagnosis and perinatal care

Meconium ileus (MI) is one of the most common causes of intestinal obstruction in the newborn accounting for 9–33% of neonatal intestinal obstructions. It is the earliest clinical manifestation of cystic fibrosis (CF), occurring in approximately 16% of patients with CF. However, MI has been reported in the absence of CF.